Conventional internal combustion engines, including port injection (PI) engines and direct injection (DI) engines, require a starting system to initiate rotation of the crankshaft to start the engine. In PI engines, fuel is delivered to the intake port via a fuel injector, which is attached to a fuel rail, and there, fuel is mixed with intake air to be delivered into the combustion chamber. As the engine rotates with the aid of a starter motor, the air-fuel mixture is inducted into the combustion chamber as the intake valve opens during the intake stroke. An ignition source is then actuated to initiate combustion causing the engine to produce enough power to rotate independently of the starting system. Conventional DI engines also require a similar starting system, although fuel is injected directly into the combustion chamber, where the fuel is mixed with air inducted during the intake stroke.
Typical starting systems for both types of engines consist of a number of discrete components and electrical circuits. The components include: a battery, with associated mounting hardware; an ignition switch; heavy duty battery cables; a magnetic switch (such as an electrical relay or solenoid); a starter motor; a ring gear; and a starter safety switch. In addition, a starter circuit and a control circuit are implemented to circumvent unwanted voltage losses associated with a direct connection of the battery, starter motor and ignition switch. The starter circuit carries the heavy current flow from the battery to the starter motor by way of a magnetic switch or solenoid and supplies power for engine cranking at startup. The control circuit couples the ignition switch to the battery and the magnetic switch, such that the heavy current flow can be regulated.
The inventors of the present invention have found certain disadvantages with these prior art starting systems. For example, detrimental losses can occur in PI and DI engines at startup. These losses include wasted fuel at startup and longer start times. Furthermore, with greater quantities of fuel required at startup, an increase in regulated emissions may occur. That is, fuel preparation (i.e. mixing and vaporization) time is limited by the cranking of the engine.
Also, the battery, heavy duty battery cables, solenoid and starter motor used with current engine starting systems are bulky components. The starter motor requires large electrical currents, typically as high as 200-300 amperes. Consequently, a heavy battery and heavy battery cables are needed, resulting in added weight and space. In addition, the need for a starting circuit adds complexity to the system.